The manufacture of butyl rubber involves the polymerization, in methyl chloride, of a mixture of isobutylene and isoprene. The product from the reactor is sent to a flash tank where it is contacted with hot water and steam to vaporize the methyl chloride and unreacted isobutylene and isoprene all of which are recycled by passage through a drier and by distillation. During the process some tertiary butyl chloride is formed which remains with the isoprene from the distillation step. The recycled isoprene contains small amounts of tertiary butyl chloride and cannot be re-used in the polymerization process and is difficult to dispose of because of the presence of the tertiary butyl chloride.
A number of techniques are known for the removal of halogenated organic compounds from hydrocarbons but so far no one procedure is satisfactory, technically and economically, for the removal of tertiary butyl chloride from isoprene so that the isoprene can be re-used in polymerization process. Chemical Abstracts Vol. 30, 2547.sup.7 describes that when n-butyl chloride is heated with calcium oxide, butene is formed. The temperature initially is 275.degree. to 285.degree. C. but after some calcium chloride has been formed the temperature can be reduced to 225.degree. C. Chemical Abstracts Vol. 29, 2874.sup.3 shows that compounds of formula C.sub.n H.sub.2n+1 Cl yield the hydrocarbon C.sub.n H.sub.2n and hydrogen chloride when heated in the presence of catalysts such as aluminum oxide, thorium oxide and calcium chloride. U.S. Pat. No. 2,920,122 describes addition of tertiary butyl chloride to a bed of calcium zeolite A which is then sealed and allowed to stand overnight following which, after removal of the excess tertiary butyl chloride, is heated to recover isobutylene. Chemical Abstracts Vol. 51, 15547 e describes the use of a heating element maintained at 800.degree. to 1100.degree. C. immersed in halogenated hydrocarbons causes removal of hydrogen chloride and shows that for tertiary butyl chloride 87% is converted to isobutylene. U.S. Pat. No. 4,921,924 describes the removal of tertiary butyl chloride from an olefin monomer mixture by contacting the monomer mixture with alumina. U.S. Pat. No. 3,864,243 teaches that hydrocarbons containing organically combined chlorine are treated by passage through high surface area, porous alumina to adsorb the chemically combined chlorine onto the alumina.